Variable speed power transmission



Jan. 28, 1964 D. D. RAZE VARIABLE SPEED POWER TRANSMISSION OriginalFiled April 5, 1956 FILE 5 3 Sheets-Sheet 2 INVENTOR. DOUGLASD- RAZEUnited States Patent 3,119,282 VARKABLE SPEED PGWER TRANSMHSSTON DouglasD. Rare, Minneapolis, Minn. Continuation of application Ser. No. 575,3713, Apr. 5, 11956. This application Ian. 31, 1961, Ser. No. 86,297Claims. (til. 74-687) This invention has relation to variable speedpower transmissions and more particularly to such transmissions in whichpower is delivered to the transmission along a drive shaft and is takenfrom the transmission along a driven shaft and in which the ratio of thespeed of the driven shaft to that of the drive shaft can be variedthrough an infinite number of increments from stationary to high speedwith respect to said drive shaft. In certain forms of the invention, theratio of the speed of the driven shaft to the speed of the drive shaftwill be a function of the power available at the drive shaft and theresistance offered at the driven shaft.

To obtain this change of ratio set of planetary gears is driven by adrive shaft and a second set of planetary gears drives a driven shaft. Aseparate pair of opposed pinion gears are each one in meshingrelationship with one set of the planetary gears and one of a pair ofgear trains connects each of said pinion gears to a corresponding piniongear in meshing relationship to the opposite planetary gear. The ratioof the speed of the driven shaft to the speed of the drive shaft can becontrolled by controlling the speed of the gear trains with respect toeach other. This can be done by applying a drag or braking action to oneor the other of the gear trains, by applying the power of one train tothe other train, or by adding power to one or both of the trains from anoutside source.

This application is a continuation of my former and co-pendingapplication, Serial No. 576,378, now abandoned, filed by me April 5,1956, and entitled Variable Speed Power Transmission.

A power transmission made according to the present invention includes adrive shaft which is positively geared to rotate a primary ring gearwhich supports primary planetary gears, a first primary pinion gearmeshed with said planetary gears and fixedly mounted on a first primaryaxle, a second oppositely disposed primary pinion gear meshed with saidplanetary gears at an opposite side of said first primary pinion gearand fixedly mounted on a second primary axle having an axis coincidentwith the axis of said first primary axle, a first primary gear wheelfixedly mounted on said first primary axle and a second primary gearwheel fixedly mounted on said secondary primary axle, a driven shaftwhich is positively geared to rotate with the rotation of a secondaryring gear which supports secondary planetary gears, a first secondarypinion gear meshed with said planetary gears and fixed to rotate on afirst secondary axle, a second oppositely disposed secondary pinion gearmeshed with said secondary planetary gears at an opposite side thereoffrom said first secondary pinion gear and fixedly mounted on a secondsecondary axis to rotate therewith, a first secondary gear wheel fixedlymounted with respect to said first secondary axle and a second secondarygear wheel fixedly mounted with respect to said second secondary axle,said first primary gear wheel and said first secondary gear wheel beingoperably connected to each other to form a first gear train and saidsecond primary gear wheel and said second secondary gear wheel beingoperably connected to each other to form a second gear train.

The ratio of the speed of the driven shaft to that of the drive shaftcan be varied by controlling the speed of the first gear train withrespect to the speed of the second gear train. This can be accomplishedin any one of a number in a transmission, a first of ways includingapplying an external drag or braking effect or holding efiect to one orthe other or both of the gear trains, by positively controlling thespeed of one of the gear trains to have a definite fixed relationship tothe speed of the other gear train through the use of auxiliary gearingbetween the two trains, by influencing the speed of one of the trainswith the other train through the use of auxiliary gearing or connectionsand adjustable clutching means or by driving one or both of the trainsfrom an external power source.

In the drawings,

MG. 1 is a horizontal sectional view of the arrangement of the powertransmitting gears of the present invention as on line 1-1 in FIG. 3with parts in section and parts broken away;

FIG. 2 is a sectional view taken on the line 2-2 in FZG. 1;

FIG. 3 is a reduced vertical sectional view taken on the line 33 in FIG.4 showing a first form of the invention;

FIG. 4 is a top plan view of the first form of the invention;

PEG. 5 is a top plan view of a power transmission made according to asecond form of the invention;

FIG. 6 is a reduced vertical sectional View taken on line 33 in PEG. 1but disclosing the second form of the invention;

FTG. 7 is a fragmentary, horizontal sectional view of a portion of apower transmission as seen in the upper right hand corner of P16. 1 butat a reduced scale and disclosing a third form of the invention;

PEG. 8 is a fragmentary, horizontal sectional view of a powertransmission as seen in the upper right hand cornor of PEG. 1 but at areduced scale and disclosing a fourth form of the invention; and

FTG. 9 is an enlarged vertical sectional view taken on the line 9 9 inFIG. 8.

Referring to the drawings and the numerals of reference thereon, a driveshaft 29 is rotatably supported in a gear box 21 and a drive shaft bevelgear 22 is fixedly mounted on said drive shaft to rotate therewith. Aprimary shaft 23 extends through the gear box 21 and is l xedlypositioned with respect thereto. A primary bevel ring gear 24 having aspider 25 extending outwardly therefrom is rotatably mounted withrespect to said primary shaft 23 as at 26. A plurality of primaryplanetary gears 27 (three as shown) are each rotatably supported withrespect to the primary ring gear 24 by means of stub shaft 28. A firstprimary bevel pinion gear 29 is in meshing relationship to each of theplanetary gears 27 and is fixedly mounted on a first primary axle 39which is rotatably mounted with respect to primary shaft 23. A firstprimary gear wheel 31 is fixedly mounted on the first primary axle St)to rotate therewith.

A second primary beveled gear 32 is in meshing relationship to each ofthe planetary gears 27 and is fixedly mounted on a second primary axle33 to rotate with respect to the primary shaft 23. A second primary gearwheel 34 is also fixedly mounted on the second primary axle 33 to rotatetherewith.

A driven shaft 35 is also rotatably mounted with respect to the gear box21 and a driven shaft bevel gear 36 is fixedly mounted thereon to be inengaged relationship with a secondary bevel ring gear 37 having a spider38 integrally connected thereto. A secondary shaft 3% extends from oneside of the gear box 21 to the other and is fixedly mounted with respectthereto. The secondary ring gear 37 is rotatably supported with respectto said secondary shaft 39 through the instrumentality of the spider 38.A plurality of secondary planetary gears 46! are each rotatablysupported with respect to said secondary ring gear 37.

A first secondary bevel pinion gear ll is fixedly 3 mounted on a firstsecondary axle 42 to rotate with respect to the secondary shaft 39. Afirst secondary gear wheel 4-3 is also fixedly mounted on said firstsecondary axle 42 to rotate therewith.

A second secondary beveled pinion gear 44 is fixedly mounted on a secondsecondary axle 45 to rotate with respect to said secondary shaft 39. Asecond secondary gear wheel 45 is likewise fixedly mounted on the secondsecondary axle 45 to rotate therewith.

As disclosed, the first primary gear wheel 31 and the first secondarygear wheel 43 are positively meshed with each other. Since these gearsare positively meshed to each other, the rotational speed of one withrespect to the other is fixed and for convenience these two gear wheelswill be referred to jointly as the first gear train 47.

Likewise, the second primary gear wheel 34 and the second secondary gearwheel 46 are positively meshed together and for convenience will bereferred to jointly as the second gear train 43.

As disclosed, the first primary gear wheel 31 has a pitch diameter threetimes the first secondary gear wheel 43 and the second primary gearwheel 34 has a pitch diameter equal to one third of that of the secondsecondary gear wheel 46. These ratios of the diameters of the primarygear Wheels to those of the secondary gear wheeis are merelyillustrative, it being understood that any other ratios may be used toobtain a desired result as long as at least one of the gear whelsrotatable on at least one of the shafts 23 and 39 has a different pitchdiameter to the other gear wheel on the same shaft.

While the ratio of the pitch diameter of the first primary gear Wheel tothe first secondary gear wheel is disclosed as being equal to the ratioof the pitch diameter of the second secondary gear wheel to the secondprimary gear wheel, it is to be understood that through the use of anysimple expedient such as a chain drive or idler gears, these ratios neednot be maintained.

The basic power transmitting arrangement as disclosed in FIGS. 1 and 2and as just described will form a basis for the four different forms ofthe invention disclosed in FIGS. 3 through 6. It is to be understood,however, that while a certain arrangement of gearing has been shown forpurposes of illustration, the actual disclosure of FIGS. 1 and 2 couldbe modified considerably without departure from the spirit of theinvention and the scope of the claims which follow.

In order to vary the speed of rotation of the driven shaft 35 withrespect to the speed of rotation of the drive shaft 20, it is necessarythat the speed of the first gear train 47 be controlled with respect tothat of the second gear train 43. This is another way of saying that thespeed of rotation of either the first primary pinion gear 29 or thesecond primary pinion gear 32 must be controlled with respect to thespeed of rotation of either the second primary pinion gear 32 or thesecond secondary pinion gear 44. There are a number of ways of effectingsuch control and four of such will now be described in connection withfour different forms of the present invention. It is to be understoodthat there may be many other possible means of control which have notbeen disclosed in the drawings or described specifically herein butwhich will come within the spirit of the invention and the scope of theclaims.

Referring now particularly to FIGS. 1 and 2 and FIGS. 3 and 4, in afirst form of the invention, a first primary upper shaft 49 is rotatablymounted in the gear box 21 and a clutch housing 50 which clutch housingis in turn mounted on a pedestal 51 on said gear box. A first primarycontrol gear 52 is mounted to rotate with the first primary upper shaft49 and to be in meshing relationship to first primary gear wheel 31. Asecond primary upper shaft 53 is rotatably mounted in gear box 21 and inthe clutch housing 50. A second primary control gear 54 is fixedlymounted on said second primary upper shaft 53 to rotate therewith. Asecondary control shaft 55 is ro- ,4 tatably mounted in the gear box 21and a first secondary control gear 56 is mounted to rotate therewith andto be in meshing relationship with the second secondary gear wheel 46. Asecond secondary control gear 57 is also rotatably mounted with 'saidsecondary control shaft 55 and is in meshing relation with a secondprimary control gear 54 which is mounted to rotate with the secondprimary upper shaft 53.

As clearly disclosed in FIG. 4, the first primary control shaft 49 andthe second primary control shaft 53 are rotatably mounted on the sameaxis. A control mechanism connected to said control shafts 49 and 53 iscomprised of a plurality of first control vanes 58 fixedly mounted onfirst primary control shaft 49 inside of clutch housing 54 and aplurality of second control vanes 59 fixedly mounted on second primarycontrol shaft 53 inside of said clutch housing. A clutch casing 65surrounds the vanes and is freely rotatably on shafts 49 and 53. Thecontrol shafts, control vanes, clutch casing and clutch housing form theelements of a conventional fluid drive or clutch with a hydraulic fluid60 inside said casing.

As is the case with all such fiuid drives or clutches, the rotationalmovement of the first control vanes 58 will have an effect upon and willtransmit power to the second control van-es 59 and rotational movementof the second control vane 59 will have an effect upon and will transmitpower to the first control vane 58 in proportion to the viscosity of thecontrol fiuid 60 and to the speed and direction of rotation of thecontrol vanes with respect to each other.

It the direction of rotation of the drive shaft 20 is such as to causethe primary bevel ring gear 24 to rotate in a positive or clockwisedirection as seen in FIG. 3, and the driven shaft 35 is standing still,and if the ratio of pitch diameter of the first primary gear wheel 31 tothe second primary gear wheel 34 is three to one and the ratio of thepitch diameter of the first secondary gear wheel 43 to the secondsecondary gear wheel 46 is one to three, the following motion will betaking place. The

first primary gear wheel 31 will be rotating in a ncga tive orcounterclockwise direction at one revolution for every four positiverevolutions of the primary bevel ring gear 24. At the same time, thesecond primary gear wheel 34 will be rotating in a positive directionfor a total of 9 revolutions. Since this second primary wheel 34- isonly one third of the diameter of the second secondary gear wheel 46 andsince it is in meshing relationship therewith, the second secondary gearwheel 46 will have turned a total of three revolutions in a negativedirection, being three times as large as the first secondary gear wheel43 and being in meshing relationship thereto, the single negativerevolution of the first primary gear Wheel 31 will account for threepositive revolutions of said first secondary gear wheel 43. This meansthat there have been three positive revolutions of the first secondarybeveled pinion gear 41 and 3 negative revolutions of the secondsecondary bevel pinion gear 44. Obviously the secondary planetary gears40 with which the secondary bevel pinion gears are meshed have simplyrotated O their axes and these axes have not moved in the plane of theirplanetary action. Consequently the second beveled ring gear 37 and thedriven shaft 35 have not moved.

As long as the relationship of the movement of the first gear train tothe second gear train remains, as has just been described, there will beno movement of the driven shaft 35. As soon as there is any influencewhich will cause a change of the relationship between the speeds of thefirst gear train and the second gear train, there will not be an equaland opposite rotation of the secondary bevel pinion gears 41 and 44 andmovement of the driven shaft 35 must result.

Referring again to PEG. 3, it will be seen that the negative movement ofsecond secondary gear wheel 46 will cause a positive movement of firstsecondary controlgear a with which it is intermeshed. This positivemovement is transmitted through the secondary control shaft 55 to thesecond secondary control gear 57 which is in turn meshed with secondprimary control gear 54 and imparts a negative movement thereto. Thesingle negative revolution of the first primary gear wheel 31 willimpart a positive movement to the first primary control gear 52 withwhich it is intermeshed. This positive movement will be transmitted tothe control vanes 58 through the instrumentality of the first primarycontrol shaft 49. Since the negative rotation of t e second primarycontrol gear is imparted to the second control vanes 59 through theinstrumentality of the second primary control shaft 53, when the drivenshaft 35 is not rotating the control vanes 58 and 59 will be rotating inopposite directions with respect to each other. Each of these sets ofcontrol vanes will tend to effect a change in the speed of rotation ofthe other set of vanes. If the speed of rotation of the drive shaft 2%is comparatively slow, and if the driven shaft 35 is connected to anyconsiderable load, there will not be sufficient power transmittedbetween the two sets of vanes to overcome this friction load and therelative speed of rotation of the parts with respect to each other willbe as previously described and consequently, the driven shaft will notturn. This would e the situation if the power transmission of the firstform of the invention was installed in an automobile, for example. Thatis, if the driven shaft 35 extended to the drive wheels of an automobileand the drive shaft 2th was the drive shaft of an automobile engine, thewheels of the automobile would not turn as long as the engine wasidling.

\Vhen, however, the speed of the engine is increased, the relative speedof rotation of the first control vanes 58 with respect to the secondcontrol vanes 59 will be increased. At some point, depending upon theviscosity of the fluid in the fluid clutching mechanism, there will be asufficient transmission of power between the first and second controlvanes so that the frictional load on the driven shaft 35 will beovercome and the driven shaft will begin to rotate.

Since the control vanes are rotating in opposite directions when thedriven shaft is standing still, the power transmitted across the vaneswill tend to cause both the:

first and second gear trains to make less revolutions per revolution ofthe drive shaft.

An analysis of the gearing will reveal that if the first gear train werestopped, a positive rotation of the primary ring gear 24 would result ina negative rotation of the secondary ring gear 37 and, of course, all ofthe drive would be through the second gear train. Since as disclosed theratio of the diameter of the second primary gear wheel to the secondsecondary gear wheel is 1 to 3, the driven shaft 35 would turn at onethird of the speed of the drive shaft 29 with a corresponding increasein power. For the purpose of this analysis, in connection with thisfirst form of the invention, it will be assumed that this clockwise orpositive rotation of the primary ring gear 24 resulting in the negativeor counter-clockwise rotation of the secondary ring gear 3'7 as seen inFIG. 3 will cause the driven shaft 35 to move the work to which ittransmits power in a forward direction.

When the driven shaft 35 is stationary and no power is transmitted, thefirst primary gear wheel 31 is rotating in a negative orcounter-clockwise direction. But, as just seen, if this wheel 31 werestanding still, a power increase of from 1 to 3 and a speed reduction offrom 3 to 1 would occur.

At the point where the power transmission across the control vanes 58and 59 is suflicient to cause any change whatsoever in the speed ofeither or both of the gear trains, movement in the driven shaft 35 musttake place to drive the work in a forward direction. The gear ratio ofthe power transmitting gears at this point will be infinitesimally low.It is to be noted that there is no necessity to cause either of thevanes to rotate in the same direction as the other. It is only necessarythat the frictional drag between the vanes be enough to cause a changein speed of the gear trains. At this point the first and second geartrains will no longer be operating in precisely the same speed ratiowith respect to each other and movement of the driven shaft in a verylow gear ratio will result. As more and more power is transmittedbetween the two sets of control vanes, as, for example when the driveshaft is considerably speeded up, a point will be reached where theslower moving first control vanes 53 will come to a standstill withrespect to the clutch housing. At this point the power will all betransmitted through the second gear train 48 and a speed reduction from3 to l and a power increase from 1 to 3 will be in effect between thedrive and driven shafts. As more power is transmitted across the fluidclutch, the vanes will begin moving in the same direction and a pointwill eventually be reached where the vanes are traveling at the samespeed. Depending upon the gear ratios of the control gears, this willresult in a predetermined high gear situation between the drive shaft Edand the driven shaft 35. When the fluid clutch is operative to have bothsets of vanes moving at the same speed, the highest gear ratio possiblein this first form of the invention has been reached.

The power transmission between the first control vanes 58 and the secondcontrol vanes 5? is a function of the speed of rotation of these vaneswith respect to each other and the viscosity of the fluid in the clutchhousing as previously indicated. Power transmission between the vanescan be increased by increasing the speed of the drive shaft id asindicated. Increase in the viscosity of the fluid will also cause anincrease in power. Here use can be made of the magnetic clutchprinciple. The magnetic coil 61 is connected by wires 62 to anappropriate rheostat 63 and power source 64. When a higher gear ratiobetween the drive and driven shafts is desired, the viscosity of thefluid oil can be increased by increasing the electrical energy to thecoil 61. The nature of the magnetic clutch is such that the magneticcoil can be energized to a point where the fluid 60 will become rigidand the vanes 5% and 52 will be fixed in their relationship to eachother.

As previously explained, an advantage of the present mechanism is thefact that the power transmission will automatically adjust itself ingear ratio as may become necessary. For any particular viscosity of oilin the fluid clutch mechanism, an equilibrium will be established whenthe power input of the drive shaft 2t) is maintained at a constant leveland the resistance to turning at the driven shaft 35 remains constant.Under these conditions, the amount of power transmitted across the fluidclutch will be constant and the gear ratio will remain constant. Nowsuppose the resistance at the driven shaft 35 is suddenly increased, as,for example, when an automotive vehicle utilizing the device suddenlystarted to climb a hill. This resistance at the ring gear 3'7 will causethe first primary gear wheel 31 to have increased tendency to rotate ina negative direction and will cause second primary gear wheel 34 to haveincreased tendency to rotate in the positive direction. The relationshipbetween the speed of the first control vanes 58 to the second controlvanes 5% will be changed accordingly and the relative speed of one withrespect to the other will be increased. This results in the operation ofthe power transmission in a lower gear ratio.

A sudden addition to the power available at the drive shaft 2% has thesame result. This sudden increase in power at ring gear 24 likewisetends to increase the tendency of the first primary gear wheel 31 torotate in a negative direction and to increase the tendency of thesecond primary gear wheel 34 to rotate in a positive direction and thischange in conditions will also cause an increase of the slippage of thefirst and secnd control vanes with respect to each other and a loweringin the gear ratio. The overall increase in the speed of the controlvanes clue to increase in power input, however, will result in anincrease in the amount of power transferred through the fluid clutch andas the power transmission adjusts to the increase in power supplied tothe drive shaft 23, a new point of equilibrium will be reached with thisgear ratio higher and the speed of the driven shaft 35 is also higher.

Referring now to FIGS. 1 and 2 and FIGS. 5 and 6, in a second form ofthe invention a first primary control shaft 49 is rotatably mounted inthe gear box 21 and in a clutch housing 5t? as was the case inconnection with the first form of the invention. Likewise, a firstprimary control gear 52 is situated in meshing relationship to firstprimary gear wheel 31. A second primary control shaft 53 is rotatablymounted in the gear box 21 and in the clutch housing 5%. A secondprimary control gear 71 is mounted to rotate with a second primarycontrol shaft 53 but is situated in clearing relationship to secondprimary gear wheel 34. An idler gear 72 is rotatably mounted withrespect to gear box 21 and is situated to be in meshing relationshipwith both second primary control gear 61 and second primary gear wheel34.

Referring now to FIG. 6 as in the previous analysis a positive orclockwise rotation of the primary bevel ring gear 24 will cause apositive rotation of the second primary gear wheel 34 and a negativerotation of the first primary gear wheel 31 when the driven shaft 35 isnot moving. Again, this is the situation when the engine driving thedrive shaft 20 is idling and the frictional or other load on the drivenshaft is appreciable. But now this positive rotation of the secondprimary gear wheel 3 will cause a negative rotation of idler gear 72 anda positive rotation of second primary control gears 71. However, aspreviously explained, the negative roration of the first primary gearwheel 31 as seen in FIG. 6 is causing a positive rotation of the firstprimary control gear 52. As in the case with the first form of theinvention, first control vanes 58 are provided on the end of the firstprimary control shaft 49 and inside of the clutch housing and casing andsecond control vanes 559 are provided on the end of the second primarycontrol shaft 53 and inside of the housing 50 and the casing 65. Asexplained in connection with the first form of the invention, in orderthat the driven shaft 35 remain stationary, the ratio of the speed ofrotation of the first gear train with respect to that of the second geartrain must remain exactly fixed. Now, however, the first control vanes58 are rotating in the same direction as the second control vanes 5'9but at different speeds. In the embodiment of the invention disclosedherein, the second control vanes 59 are traveling at a faster rate thanare the first control vanes 58 when the driven shaft 35 is not moving.

As previously analyzed, the positive rotation of second primary gearwheel 34 which now also causes the second control vane 59 to move in apositive direction tends to cause the secondary bevel ring gear 37 to berotated in a negative or counter-clockwise direction. This positiverotation of second primary gear wheel 34 will tend to be slowed down bythe action of the first control vanes 58 on the second control vanes 59;and the tendency for the secondary bevel ring gear 37 to be moved in anegative direction by second gear train 4-8 will be reduced as saidsecond gear train 43 is slowed down.

Since the driven shaft 35 is standing still under idling conditions andsince the action of the power transmitted through the second gear trainwas to cause secondary bevel ring gear 37 to move with a negativerotation, it is obvious that the power transmitted through the firstgear train 47 is tending to cause the ring gear to have a positiverotation. In other words, a negative rotation of the first primary gearwheel 31 acting through the first secondary gear wheel -23 tends tocause the secondary bevel ring gear 37 to rotate in a positivedirection. But the action of the second control vanes 59 on the firstcontrol vanes 53 will tend to cause the relative speed of the negativerotation of first primary gear wheel 31 to be increased. This increasein relative speed of negative rotation of the first primary gear wheel31 will increase the tendency of the secondary bevel ring gear 37 torotate in a positive direction. Thus it will be seen that both theaction of the first control vanes 58 speeding up and the control va es5'9 slowing down as the power transmitted between these vanes isincreased will tend to cause the secondary ring gear 37 to increase itsrotation in a positive direction. For the purpose of the analysis of thesecond form of the invention, therefore, rotation of the secondary ringgear 37 in a positive direction will be assumed to cause the drivenshaft 35 to be moved to drive the load or perform the work in a forwarddirection.

As soon as there is sufficient power transmitted between the controlvanes' 58 and 59 to cause change in the relative speed of the first geartrain with respect to the second gear train 48, the driven shaft 35 willdrive the work in a forward direction. This will happen as soon as thepower transmitted between the vanes overcomes the frictional loadtending to hold the driven shaft 35 at rest. As the power transfer inthe fluid clutch is further increased, the speed of the second controlvanes will be further retarded and the speed of the first control vanes58 will be further increased. This will result in an increase in thespeed of rotation of the driven shaft 35 with respect to the drive shaft20. In other words, an increasingly hi h gear ratio will result from anincrease in power transfer between the clutch vanes.

If the relationship between the diameters of the first primary controlgear 52 and the first primary gear wheel 31 are such that the firstprimary control shaft 49 rotates twice to every revolution of the firstprimary axle 30; and if the pitch diameter of the second primary controlgear 71 and the second primary gear wheel 34 are such that the secondprimary control shaft 53 rotates twice for every rotation of the secondprimary axle 33, then if a point could ever be reached where firstcontrol vanes 58 and second control vanes 59 became locked with respectto each other, the first primary axle 30 would be rotating exactly thesame number of times as the second primary axle 33 but in an oppositedirection. Obviously this could only happen when the primary bevel ringgear 24 was stationary so that the primary planetary gears 27 would berotating with the first primary bevel pinion gear 29 and the secondprimary bevel pinion gear 32 without movement of the axes of theplanetary gears in their planetary orbits.

From the above analysis it will be seen that as the power at drive shaft2% is increased, and as the power transmitted between the first andsecond control vanes of the fluid clutch is increased, the speed of thecontrol vanes with respect to each other will be decreased and the gearratio will be increased. There is no limit to the increase in the gearratio except the limit of the amount of power which can be transmittedthrough the fluid clutch and the amount of power which can be suppliedto the drive shaft 20.

In other words, the relative speed of the driven shaft 35 with respectto the drive shaft 23 will keep increasing as the power at the driveshaft is increased and the power transmitted across the fluid clutch isincreased until the resistance of the driven shaft 35 and the frictionlosses in the apparatus are equal to the power input at the drive shaft20.

As stated in connection with the first form of the invention, a magneticfluid clutch can be utilized to increase and decrease at will theviscosity of the fluid 60 between the vanes and consequently increaseand decrease the power transmitted between the vanes.

Referring now to FIGS. 1 and 2 and FIG. 7, in a third form of theinvention the portion of the power transmission seen at the upper righthand corner of 31 is modified to appear as in PEG. 7. The first primarygear wheel 31 is provided with an outwardly extending annular brake drum$1 integral therewith. An inwardly extending hub 82 in which the primaryshaft 23 is journaled is provided with an annular fiange 83 on whichthere is supported hydraulic brake mechanism of any usual or preferredconstruction including a brake arm and a brake shoe 85. A pipe 36 is forcarrying hydraulic fluid for exerting pressure on the braking mechanismto cause the brake shoe S to be brought into braking contact with theinterior surface of the brake drum 81.

As has been explained in connection with the other forms of theinvention, when the driven shaft 35 is at rest and the drive shaft 2% isrotating, there will be a fixed relationship between the speed of thefirst gear train 47 and the second gear train 48. Any means of changingthe relationship of the speeds of these gear trains to each other willresult in movement of the driven shaft 35. The brake disclosed in FIG. 7can provide such a change in this relationship. When hydraulic pressureis exerted through the pipe 86 from a source (not shown) so that thebrake shoe 85 is brought to bear on the brake drum 81, the first primarygear wheel 31 will tend to slow down. As soon as this gear wheel 31slows down in relationship to the movement of the second primary gearwheel 34 for example, movement will take place in the driven shaft 35.The initial movement taking place will be at an extremely low gearratio.

As further pressure is brought to bear on the brake drum 81, the firstprimary gear wheel 31 will eventually come to rest and be held in thatcondition. At this time all of the drive through the transmission willbe through the second gear train. Since, as disclosed, the ratio of thepitch diameter of the second primary gear wheel 34 to the secondsecondary gear wheel 46 is one to three, the driven shaft 35 will beturning at /3 of the speed of the drive shaft 2% and will have threetimes the power of the drive shaft less friction losses in thetransmission. When a power transmission made according to a third formof the invention is applied to an automobile or a truck, it is obviousthat when a braking mechanism of FIG. 7 is applied to hold the firstprimary gear wheel 31 and consequently the first gear train in fixedposition with relation to the gear box, a positive low gear drivethrough the second gear train 48 results.

Obviously, any other convenient or desirable gear ratio of the firstgear train and/ or the second gear train could be used to provide for apositive drive to the second gear train. Also, it will be obvious thatthe braking arrangement disclosed in FIG. 7 could be applied equallywell to the second secondary gear wheel 46 and that when this gear wheelwas locked in fixed position with respect to the gear box 21, a positivedrive through the first gear train would result in which, as disclosedherein, the driven shaft 35 would turn at three times the speed of thedrive shaft 29 and the power available would be one third of thatavailable at the drive shaft less friction losses in the powertransmission.

Referring now to FIGS. 1 and 2 and FIGS. 8 and 9, in a first form of theinvention, the structure disclosed in the upper right hand corner ofFIG. 1 could be modified to be as disclosed in FIGS. 8 and 9. An annulardrum extends outwardly from the gear box 21 in concentric relationshipto the primary shaft 23. A boss 92 is integral with and extendsoutwardly from first primary gear wheel 31 and includes tapered lockingsurfaces 93 parallel to the axis of rotation of said gear wheel anddriving surfaces 94 lying in planes passing through the axis of saidgear wheel. A plurality of cylindrical pins 95 are situated in the spaceprovided between the tapered locking surfaces 93 and the interiorsurface of the annular drum 91. This whole arrangement is denotedgenerally as antibackup mechanism 96.

As set out in connection with the first form of the invention, when thedriven shaft 35 is at rest, and the drive shaft 20 is rotating, firstprimary gear wheel 31 must rotate in a negative direction as seen fromthe bottom of FIG. 1. Since section line 9-9 is taken from the oppositedirection, this same movement will appear as a positive or clockwisemovement in FIG. 9. But the cylindrical pins and the tapered lockingsurfaces 93 of the boss 92 are so situated that as the gear wheel 31 andconsequently the boss 92 attempts to rotate in a positive direction asseen in FIG. 9, these pins 95 will become wedged between the lockingsurfaces 93 and the interior surface of the annular drum 91 and the gearwheel 31 will be unable to rotate. As explained in connection with thethird form of the invention, this locking of gear wheel 31 andconsequently the first gear train 47 will result in a positive driveentirely through the second gear train 48. As disclosed this means thatthree times the power available at the drive shaft 20 less the frictionlosses in the power transmission will be available at the driven shaft35 at one third of the speed of the drive shaft. This will then be thelowest gear ratio of which the power transmission made according to thefourth form of the invention is capable of delivering. As the powerdeveloped at the drive shaft 2%) is increased and as the load on thedrive shaft 35 is decreased, the powered transmission will move into ahigher gear ratio and the first primary gear wheel 31 will be free torotate in a negative or counter-clockwise direction as seen in FIG. 9.

This movement to a higher gear ratio can be obtained by providing abrake such as disclosed in the third form of the invention on the actionof the second gear train or by some such means as disclosed in the firstand second forms of the invention.

The anti-backup mechanism 96 can also be used to limit the highest gearratio which will be delivered by the power transmission. In order to dothis, the boss 92 would be constructed to have the tapered lockingsurfaces 93 in reverse relationship to that shown in FIG. 9. The gearwheel 31 would then be free to turn in the negative or counter-clockwisedirection as seen in FIG. 9 and Would be prevented from turning in thepositive direction. Then when some means such as disclosed in the firstthree forms of the invention or some other means was used to vary therelationship of the speed of the gear trains with respect to each other,the driven shaft 35 would initially move at an extremely low gear ratio.As the ratio of the speed of the gear trains to each other was changedfurther, the overall gear ratio of the power transmission would gethigher until a point was reached where the gear wheel 31 would come to astop. At this point the drive would be entirely through the second geartrain and the overall gear ratio from the drive shaft to the drivenshaft would be such that the power available at the driven shaft wouldbe three times that available at the drive shaft less losses. Since theanti-backup mechanism 96 would now prevent the gear 31 and the boss 92from rotating in a negative direction as seen in FIG. 9 (positivedirection as seen in FIG. 1), the gear ratio delivered by the powertransmission could never be any higher than 1 to 3. This could be usefulwhere the gear transmission was employed on tractors, hoistingmechanisms, or the like.

In order to limit the output of a power transmission as herein disclosedto a low gear of from 1 to 3 and to a high gear of 3 to 1, theanti-backup mechanism 96 will be installed as disclosed in FIG. 9 and asimilar mechanism will be installed in relationship to the second geartrain to prevent rotation of second secondary gear wheel 46 in apositive direction as seen from the bottom of FIG. 1.

As heretofore stated, the basic concept of this invention is theprovision of a positive gear transmission in which the powertransmitting gears are always in mesh with each other and in which theratio of the speed of these power transmitting gears to each other canbe varied to vary the overall gear ratio of the power transmission.While the various means of va rying the ratios of the power transmittinggear trains to each other disclosed herein are believed to be inventive.it is to be understood that numerous other means could be utilized toaccomplish the same purpose. For example, in the first form of theinvention, a friction clutch could replace the fluid clutch mechanismand the control gearing could be completely rearranged. Likewise, inconnection with the third form of the invention, the brake mechanismdisclosed could be, under some circumstances replaced by a lockingmechanism through the instrumentality of which the primary gear wheel 31could be locked against movement. Any combination of the controlmechanisms disclosed could be utilized in a single power transmissionand provision could be made for the various mechanisms to be operativein the system at certain times and inoperative at other times.

What is claimed is:

1. A power transmission including a gear box, a drive shaft rotatablymounted in said gear box, a driven shaft rotatably mounted in said gearbox, a primary ring gear rotatably mounted to be driven by said driveshaft, a secondary ring gear rotatably mounted to drive said drivenshaft, a primary planetary gear mounted to revolve with said primaryring gear and to have its axis radially aligned with the axis ofrotation of said primary ring gear, first and second primary piniongears rotatably mounted on said axis of said primary ring gear and inmeshing relationship with said primary planetary gear, a secondaryplanetary gear mounted to revolve with said secondary ring gear and tohave its axis radially aligned with the axis of rotation of saidsecondary ring gear, first and second secondary pinion gears rotatablymounted on said axis of said secondary ring gear and in meshingrelationship with said secondary planetary gear, a first gear trainoperably connected to said first primary pinion gear and said firstsecondary pinion gear to cause said first and second primary piniongears to rotate with respect to each other in a predetermined gear ratiorelationship and a second gear train operably connected with said secondprimary pinion gear and with said second secondary pinion gear to causesaid second primary and said second secondary pinion gears to rotatewith respect to each other in a predetermined gear ratio different fromsaid first predetermined ratio, and control means controlling the speedof said first and second gear trains with respect to each otherconstituted as a first control shaft drivably connected to said firstgear train and mounted to rotate in response to rotation of said firstgear train, a second control shaft drivably connected to said secondgear train and mounted to rotate in response to the rotation of saidsecond gear train and means connected to said control shafts fortransmitting rotative power therebetween.

2. In combination with a source of power, a power transmissionconsisting of a base member, a primary differential mechanism mountedwith respect to said base member and having an input member receivingpower from said outside source and first and second primary axles eachoperably connected with said input member and each drivably connected toand transmitting power flowing through said primary differentialmechanism, a secondary differential mechanism mounted with respect tosaid base member and having an output member tran mitting power fromsaid secondary differential mechanism and first and second secondaryaxles each operably connected with said output member and each drivablyconnected to and transmitting power flowing through said secondarydifferential mechanism, first means drivably connecting and causing saidfirst secondary axle to rotate in response to rotation of said firstprimary axle, second means drivably connecting and causing said secondsecondary axle to rotate in response to rotation of said second primaryaxle, and control means other than said differential mechanisms operablyconnected to and transmitting power between said first axles and saidsecond axles, said control means being connected to said first and saidsecond means and including a mechanism controlling the amount of powertransmitted between said first axles and said second axles in responseto the relative speed of rotation of said first axles with respect tothe speed of rotation of said second axles.

3. In combination with a source of power, a power transmissionconsisting of a journal structure, a primary differential mechanismmounted with respect to said journal structure and having an inputmember receiving power from said outside source and first and secondprimary axles each operably connected with said input member and eachdrivably connected to and transmitting power flowing through saidprimary difierential mechanism, a secondary differential mechanismmounted with respect to said journal structure and having an outputmember transmitting power from said secondary differcntial mechanism andfirst and second secondary axles each operably connected with saidoutput member and each drivably connected to and transmitting powerfiowing through said secondary differential mechanism, first drive meansdrivably connecting said first secondary axle and said first primaryaxle and causing said first secondary axle to rotate at a fixed ratio inresponse to rotation of said first primary axle, second drive meansdrivably connecting said second secondary axle and said second primaryaxle and causing said second secondary axle to rotate at a differentratio in response to rotation of said second primary axle, and controlmeans other than said differential mechanisms transmitting power betweensaid first axles and said second axles, said control means beingconnected to said first and second drive means and in cluding amechanism controlling the amount of power transmitted between said firstaxles and said second axles in response to relative speeds of said inputmember and said output member.

4. A variable speed power transmission comprising, a frame includingjournal structure, a source of rotary power, a primary differentialmechanism mounted upon said journal structure, an input member connectedwith said source of rotary power in driven relation and con nected withsaid differential mechanism in driving relation, first and secondprimary axles each operably connected with said primary differentialmechanism for transmitting power flowing through said primarydifferential mechanism, a secondary differential mechanism mounted uponsaid journal structure, first and second secondary axles operablyconnected to said secondary differential mechanism and transmittingpower flowing through said secondary differential mechanism, a drivenrotary member connected in driven relation with said secondarydifiierential mechanism, first drive means connected to said firstprimary axle and said first secondary axle in driving relation andcausing said first secondary axle to rotate at a predetermined ratio inresponse to rotation of said first primary axle, second drive meansconnected to said second secondary axle and said second primary axle indriving relation and causing said second secondary axle to rotate at apredetermined and different ratio in response to rotation of said secondprimary axle, and control means extending between, and operativelyconnected with said first and second drive means and includ ing controlmechanism and shaft means drivably connecting said control mechanism toboth of said drive means for constantly transmitting rotative power fromone of said drive means to the other of said drive means in response torelative speed of rotation of said first drive means with respect to thespeed of rotation of said second drive means.

5. The structure defined in claim 4 wherein said control mechanismincludes a fluid clutch.

6. The structure defined in claim 5 wherein the said 13 fluid clutchincludes a viscous liquid, and means con nected to said fluid clutch forvarying the viscosity of said liquid.

7. The structure defined in claim 4 wherein said shaft means includes apair of axially aligned control shafts 5 connected to each other by saidcontrol mechanism.

8. The structure defined in claim 4 wherein said control mechanismincludes a fluid clutch and said shaft means includes a pair of axiallyaligned shafts each of Which is drivably connected at one of its ends tosaid fluid 10 clutch and to one of said drive means at its other end.

References Cited in the file of this patent UNITED STATES PATENTS

1. A POWER TRANSMISSION INCLUDING A GEAR BOX, A DRIVE SHAFT ROTATABLYMOUNTED IN SAID GEAR BOX, A DRIVEN SHAFT ROTATABLY MOUNTED IN SAID GEARBOX, A PRIMARY RING GEAR ROTATABLY MOUNTED TO BE DRIVEN BY SAID DRIVESHAFT, A SECONDARY RING GEAR ROTATABLY MOUNTED TO DRIVE SAID DRIVENSHAFT, A PRIMARY PLANETARY GEAR MOUNTED TO REVOLVE WITH SAID PRIMARYRING GEAR AND TO HAVE ITS AXIS RADIALLY ALIGNED WITH THE AXIS OFROTATION OF SAID PRIMARY RING GEAR, FIRST AND SECOND PRIMARY PINIONGEARS ROTATABLY MOUNTED ON SAID AXIS OF SAID PRIMARY RING GEAR AND INMESHING RELATIONSHIP WITH SAID PRIMARY PLANETARY GEAR, A SECONDARYPLANETARY GEAR MOUNTED TO REVOLVE WITH SAID SECONDARY RING GEAR AND TOHAVE ITS AXIS RADIALLY ALIGNED WITH THE AXIS OF ROTATION OF SAIDSECONDARY RING GEAR, FIRST AND SECOND SECONDARY PINION GEARS ROTATABLYMOUNTED ON SAID AXIS OF SAID SECONDARY RING GEAR AND IN MESHINGRELATIONSHIP WITH SAID SECONDARY PLANETARY GEAR, A FIRST GEAR TRAINOPERABLY CONNECTED TO SAID FIRST PRIMARY PINION GEAR AND SAID FIRSTSECONDARY PINION GEAR TO CAUSE SAID FIRST AND SECOND PRIMARY PINIONGEARS TO ROTATE WITH RESPECT TO EACH OTHER IN A PREDETERMINED GEAR RATIORELATIONSHIP AND A SECOND GEAR TRAIN OPERABLY CONNECTED WITH SAID SECONDPRIMARY PINION GEAR AND WITH SAID SECOND SECONDARY PINION GEAR TO CAUSESAID SECOND PRIMARY AND SAID SECOND SECONDARY PINION GEARS TO ROTATEWITH RESPECT TO EACH OTHER IN A PREDETERMINED GEAR RATIO DIFFERENT FROMSAID FIRST PREDETERMINED RATIO, AND CONTROL MEANS CONTROLLING THE SPEEDOF SAID FIRST AND SECOND GEAR TRAINS WITH RESPECT TO EACH OTHERCONSTITUTED AS A FIRST CONTROL SHAFT DRIVABLY CONNECTED TO SAID FIRSTGEAR TRAIN AND MOUNTED TO ROTATE IN RESPONSE TO ROTATION OF SAID FIRSTGEAR TRAIN, A SECOND CONTROL SHAFT DRIVABLY CONNECTED TO SAID SECONDGEAR TRAIN AND MOUNTED TO ROTATE IN RESPONSE TO THE ROTATION OF SAIDSECOND GEAR TRAIN AND MEANS CONNECTED TO SAID CONTROL SHAFTS FORTRANSMITTING ROTATIVE POWER THEREBETWEEN.